#include<stdio.h>

int add(int x1 = 5, int x2 = 10);
int dec(int x1, int x2 = 1);

int fun(void)
{
    int add(int x1 = 1, int x2 = 2);
    return add();
}

int main(int argc, char *argv[])
{
    printf("add = %d\n", add());
    printf("dec = %d\n", dec(5));
    printf("fun = %d\n", fun());
    printf("add = %d\n", add());
    return 0;
}

int add(int x1, int x2)
{
    return x1 + x2;
}

int dec(int x1, int x2)
{
    return x1 - x2;
}
